This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2000-231865, filed Jul. 31, 2000, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an improvement of the format of an information recording medium such as an optical disk or the like. The present invention also relates to an information reproduction apparatus for reproducing data recorded on such information recording medium, and an information recording apparatus for recording data on such information recording medium.
2. Description of the Related Art
An optical disk apparatus that reads/writes digital data mainly performs CAV recording in which the rotational speed is constant. On an optical disk to be processed, digital data is recorded to form a spiral signal track. Optical disks may include a read-only disk on which data have been recorded as an embossed pattern on the disk surface in the manufacture, and a disk which has both a recordable region and a read-only region, in addition to a recordable recording/reproduction type disk.
Upon reproduction, a motor rotates an optical disk, and an optical head reads out a signal recorded on the optical disk using a laser beam. In the optical head, a light beam emitted by an LD (laser diode) is focused on a pit sequence on a track formed on the optical disk by an objective lens. The light beam reflected by the optical disk is focused on a photodetector via a focusing lens, thus obtaining a reproduction signal.
A signal output from the optical head is amplified by a reproduction amplifier, and then undergoes waveform equalization by a waveform equalizer. The waveform equalizer comprises a filter having, e.g., high-frequency emphasis characteristics to facilitate identification of digital data successively recorded along a track.
In order to reconstruct original data from the recorded digital data, the equalized reproduction signal must be converted into binary data of 0 or 1, and data must be identified in synchronism with clocks. No clock signal is recorded especially on the optical disk. For this reason, a PLL circuit generates a reproduction clock signal based on the reproduction signal. On the other hand, an identification circuit outputs binary identification data in synchronism with the reproduction clock signal output from the PLL circuit.
Upon recording, a header extraction circuit detects a header field. The header field records address information and the like. The current position is detected based on the address information recorded in the header, and the optical head is moved on the basis of a deviation between the current position and recording start position. When the optical head has reached the recording start position, recording of objective data starts.
The optical disk is divided into a plurality of doughnut-like zones, and a constant rotational speed of the disk is maintained within each zone. Data is recorded while the rotational speed is constant. In a given zone, the recorded data size per rotation of the disk is constant. In other words, respective zones have different recorded data sizes per rotation.
Headers are laid out on the disk at a given spacing. An integer number of headers are laid out per rotation. Due to different distances per rotation on the inner and outer peripheral sides of the disk, headers are radially laid out in a zone. A discontinuous portion is formed between neighboring zones. The number of headers per rotation differs depending on zones, and the number of headers increases toward the outer periphery. Since the header positions in neighboring tracks are aligned except for a zone boundary portion, headers can be prevented from being destroyed by operation errors, and crosstalk disturbance from a header to recorded data with respect to a reproduction signal can be prevented.
However, when the aforementioned header layout is adopted, since the rotational speeds of the disk at a boundary portion of zones become discontinuous, data cannot be recorded near the boundary of zones. Furthermore, since the data size per rotation is constant within a zone, the linear recording density on the outer peripheral side becomes lower than that on the inner peripheral side of a zone. As a result, the data recording efficiency on the whole disk drops.
On the other hand, in order to improve the data recording density and to increase the recording capacity of the disk, a constant linear recording density scheme is suitable. However, when recording is done using the constant linear recording density scheme, the recorded data size per rotation changes in proportion to the radius from the inner to the outer periphery of the disk. Hence, when a header is laid out at the head position of each constant recorded data block, the headers are scattered at arbitrary locations on the disk.
As a result, when a track error has occurred during recording due to operation errors, data may be inadvertently recorded on a header to destroy the header. Since the header positions between neighboring tracks are not aligned, a reproduction signal of recorded data deteriorates by a header signal from a neighboring track.
In this way, in the conventional header layout method, when recording is done using the constant rotational speed scheme, the average data recording efficiency lowers to reduce the storage capacity of the disk.
When recording is done using the constant linear density scheme to improve the data recording efficiency, since header positions are not aligned between neighboring tracks, the system reliability and reproduction signal quality suffer.
The present invention has been made in consideration of the above situation, and has as its object to provide the following information recording medium, information reproduction apparatus, and information recording apparatus:
a highly reliable information storage medium which can minimize a positional deviation between headers of neighboring tracks without reducing the overall storage capacity, an information reproduction apparatus which can reproduce data recorded on the highly reliable information storage medium, and an information recording apparatus which can record data on the highly reliable information storage medium.
In order to solve the aforementioned problems and to solve the above object, an information recording medium, information reproduction apparatus, and information recording apparatus of the present invention have the following arrangements.
(1) An information recording medium of the present invention has a spiral track, the spiral track has one or more header fields per round of the spiral track, and a data field located between neighboring header fields, and the data field has a variable length corresponding to an integer multiple of a predetermined length Lw so as to minimize a deviation between an n-th header field in a predetermined round of the spiral track, and an n-th header field in a round different from the predetermined round in a track direction.
(2) The present invention is directed to an information reproduction apparatus for reproducing an information recording medium,
the information recording medium having a spiral track, the spiral track having one or more header fields per round of the spiral track, and a data field located between neighboring header fields, and the data field having a variable length corresponding to an integer multiple of a predetermined length Lw so as to minimize a deviation between an n-th header field in a predetermined round of the spiral track, and an n-th header field in a round different from the predetermined round in a track direction, and
the information reproduction apparatus of the present invention comprising rotation control means for controlling a rotational speed of the information recording medium to obtain a constant linear velocity, header processing means for detecting the header field from the information recording medium which undergoes the rotation control of the rotation control means, and reproducing address information from the header field, and reproduction means for reproducing target data from the data field on the basis of the address information obtained by the header processing means.
(3) The present invention is directed to an information recording apparatus for recording data on an information recording medium,
the information recording medium having a spiral track, the spiral track having one or more header fields per round of the spiral track, and a data field located between neighboring header fields, and the data field having a variable length corresponding to an integer multiple of a predetermined length Lw so as to minimize a deviation between an n-th header field in a predetermined round of the spiral track, and an n-th header field in a round different from the predetermined round in a track direction, and
the information recording apparatus of the present invention comprising rotation control means for controlling a rotational speed of the information recording medium to obtain a constant linear velocity, header processing means for detecting the header field from the information recording medium which undergoes the rotation control of the rotation control means, and reproducing address information from the header field, and recording means for recording target data on the data field on the basis of the address information obtained by the header processing means.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.